Mustard is a must-have pantry staple. We wanted to make a simple, preservative-free version at home, choosing both the sharpness and sweetness to our taste. We started with only four ingredients: yellow and brown mustard seeds, vinegar, and water. Yellow mustard seeds are milder, whereas brown mustard seeds add a more pungent, spicier bite. By using both types in a 1:1 ratio, we produced a well-rounded flavor. We used cider vinegar, instead of distilled white vinegar, to round out the intensity of the mustard seeds. Before processing the ingredients together, we softened the seeds by soaking them for at least 8 hours so that the mustard had a creamy consistency. Reserving 1/2 cup of the soaked mustard seeds separately and stirring them back into the pureed mustard gave it the hallmark grainy consistency we were after. Two tablespoons of brown sugar, along with a small amount of salt, tempered the mustard’s bite.

The real trick to deepening the flavor of this simple mustard, however, was to let it sit at room temperature for one to two days. During this sitting time, the ingredients melded and developed a well-rounded, spicy flavor. The longer the mustard sat at room temperature, the more spicy it became. The key, we found, was to taste it often during this two-day period and refrigerate it as soon as it reached our preferred level of heat. Although refrigeration will halt the formation of the spicy compounds, the overall flavor of the mustard will continue to deepen and mature throughout its shelf life. This mustard cannot be processed for long-term storage.

Ingredients

3/4 cup cider vinegar

1/2 cup water

1/3 cup yellow mustard seeds

1/3 cup brown mustard seeds

2 tablespoons packed light brown sugar

1 1/4 teaspoons salt

Directions

Combine vinegar, water, yellow mustard seeds, and brown mustard seeds in medium bowl. Cover with plastic wrap and let stand at room temperature for at least 8 hours or up to 24 hours.

Using funnel and spoon, portion mustard into two 1-cup jars. Cover and let mustard stand at room temperature until it has reached desired spiciness, 1 to 2 days; mustard will become spicier as it rests. Once desired spice level has been reached, refrigerate and serve. (Mustard can be refrigerated for up to 6 months; once refrigerated, flavor will continue to mature but will not become more spicy.)

A tip from The City Cook -- If you're looking to buy both yellow and brown mustard seeds, Kalustyan's, located on Lexington Avenue in Manhattan, is a great source. In addition to their store, you can buy at their website, Kalustyans.com.